This application relates to a clutch having two driven discs. More particularly, the present invention relates to an assembly for properly positioning an intermediate plate relative to the two driven discs.
Clutches having a pair of driven discs with an intermediate plate dipsosed between the discs are known. A flywheel is disposed at one end of the two dics and is fixed to a clutch cover at the other end of the two discs to enclose the clutch. Rotational velocity is selectively transmitted from the flywheel to drive the discs.
The intermediate plate between the two discs must be accurately positioned to provide proper clearance between the discs and the intermediate plate. Several prior art systems have developed various arrangements to properly position this intermediate plate. In one system, a plurality of positioning pins slidably mounts the intermediate plate between the two discs. The positioning pins and intermediate plate move a small distance with clutch engagement towards the flywheel. When the clutch is disengaged the intermediate plate and positioning pin move the same small distance away from the flywheel. The intermediate plate will typically be frictionally engaged on the positioning pin such that it may move along the positioning pin towards the flywheel to compensate for wear on the discs.
In initially positioning the intermediate plate, the clutch is engaged and the positioning pins are forced into contact with the flywheel and move relative to the intermediate plate. With the clutch engaged, the intermediate plate is in the proper position for clutch engagement. Thus, the intermediate plate is positioned on the positioning pins in the proper clutch engaged position whenever the positioning pins are in contact with the flywheel. Once the clutch has been initially set up, the positioning pins provide a stop for movement of the intermediate plate against the flywheel which defines the proper clutch engage position. The clutch cover typically provides a stop for the clutch disengaged position.
Problems have arisen in these prior art clutches since the clutch cover blocks access to the positioning pins making it difficult to initially position them relative to the flywheel. In response to this problem some prior art clutches have provided an aperture through the cover for each positioning pin, and some member is inserted through this aperture to contact the positioning pin and force it against the flywheel. Typically, a set pin is inserted through the aperture in the cover and is hit with a hammer or similar tool to move the positioning pin to a desired position. Such a system is disclosed in U.S. Pat. No. 4,601,373.
While the above-described prior art clutch does overcome some problems, there are still deficiencies in the clutch. First, a set pin inserted through the aperture to contact the positioning pin and force it against the flywheel, may not be directed along an axis coaxial to the positioning pin. Thus, the force transmitted to the positioning pin could be skewed off the axis of the positioning pin. The positioning pin may bind within the intermediate plate, and result in some misalignment. Further, these prior art systems require close work to initially position the intermediate plate since the set pin must be inserted into each of the apertures individually to ensure proper placement of the positioning pins.
In the prior art, the aperture through the cover could not be coaxial with the positioning pin since the cover provides a stop for the positioning pin in the disengaged position. Movement of the positioning pin to the clutch disengaged position might cause it to move into the aperture, which would be undesirable. As an alternative, it was suggested that the aperture be made of a smaller diameter than the diameter of the positioning pin. These two requirements resulted in a problem with some prior art systems wherein the force transmitted to the positioning pin was directed along an axis that was not coaxial to the axis of the positioning pin, and was also over a relatively small surface area.
It is an object of the present invention to overcome the above-discussed limitations in the prior art clutches.